diff --git a/lib/traits/elements.php b/lib/traits/elements.php
index 99b7e99..2fd04e9 100644
--- a/lib/traits/elements.php
+++ b/lib/traits/elements.php
@@ -548,7 +548,7 @@ public function addParamsGrouping($fields = [])
     {
         if (is_array($fields) && !empty($fields))
         {
-            $this->groupingParams = array_merge($this->groupingParams, $fields);
+            $this->groupingParams = array_merge(is_array($this->groupingParams) ? $this->groupingParams : [], $fields);
         }
     }